code: def __str__(self):
      assert (
          self.speaker.name is not None
      ), "Speaker name needs to be set for generating utterance string"
      return f"{self.speaker.name}: {self.text}" + "\n"
  
file_path: H2O/h2o_hf/helm/src/helm/benchmark/scenarios/dialogue_scenarios.py
imports: import csv
  import os
  import pandas
  from dataclasses import dataclass
  from typing import Dict, List, Optional
  from helm.common.general import ensure_file_downloaded
  from helm.common.hierarchical_logger import hlog
  from .scenario import Scenario, Instance, Reference, TRAIN_SPLIT, VALID_SPLIT, TEST_SPLIT, CORRECT_TAG, Input, Output
label_desc: Use image node_id 1 for calling the Utterance obj's underlying member method code with example usage: obj.__str__() and returns: unknown